Hi. Co-editor of ActivityPub here. Nothing about ActivityPub's design is Twitter-esque specific. In fact it largely comes from pump.io's design which is much more Facebook-like than Twitter's design. We also built ActivityPub so that Diaspora could use it. That's the whole reason collections are addressable, in order to be able to handle the design of Diaspora's aspects.
I'm curious about your thoughts on https://github.com/denschub/schubio/blob/master/_posts/2018-... and https://github.com/denschub/schubio/blob/master/_posts/2018-... specifically. As someone who is new to both the Diaspora* and ActivityPub protocols, the Diaspora* patterns of publishing messages seem to be much easier for me to reason about particularly for semi-private FB-esque social networks (as opposed to mostly public social networks akin to Twitter or Youtube comments). My reactions echo what is mentioned in those links, but maybe I'm just thinking about it wrong.
